Investigating the Influence of Oil Shale Ash and Basalt Composite Fibres on the Interfacial Transition Zone in Concrete
Iveta Nováková,
Ashfaque Ahmed Jhatial,
Sofija Kekez,
Eirik Gjerløw,
Volodymyr Gulik,
Karunamoorthy Rengasamy Kannathasan,
Mindaugas Vaišnoras,
Andrejs Krasnikovs
Affiliations
Iveta Nováková
Department of Building, Energy and Material Technology, Faculty of Engineering and Technology, The Arctic University of Norway, Lodve Langesgate 2, N-8514 Narvik, Norway
Ashfaque Ahmed Jhatial
Department of Building, Energy and Material Technology, Faculty of Engineering and Technology, The Arctic University of Norway, Lodve Langesgate 2, N-8514 Narvik, Norway
Sofija Kekez
Department of Building, Energy and Material Technology, Faculty of Engineering and Technology, The Arctic University of Norway, Lodve Langesgate 2, N-8514 Narvik, Norway
Eirik Gjerløw
Department of Building, Energy and Material Technology, Faculty of Engineering and Technology, The Arctic University of Norway, Lodve Langesgate 2, N-8514 Narvik, Norway
Volodymyr Gulik
Institute of Physics, University of Tartu, W. Ostwaldi 1, 50411 Tartu, Estonia
Karunamoorthy Rengasamy Kannathasan
Department of Theoretical Mechanics and Strength of Material, Riga Technical University, Ķīpsalas Iela 6a, Centra Rajons, LV-1048 Riga, Latvia
Mindaugas Vaišnoras
Lithuanian Energy Institute, Breslaujos St. 3, LT-44403 Kaunas, Lithuania
Andrejs Krasnikovs
Department of Theoretical Mechanics and Strength of Material, Riga Technical University, Ķīpsalas Iela 6a, Centra Rajons, LV-1048 Riga, Latvia
The interfacial transition zone (ITZ) is the weakest phase in concrete, characterised by higher porosity and being prone to microcrack formation. Additionally, the ITZ is created when dispersed fibre reinforcement is present. Although fibres improve flexural strength, they can negatively impact other properties. This research investigates the ITZ of fibre-reinforced concrete where macro-basalt fibres (BFs) and oil shale ash (OSA), as an SCM, were used with the aim of modifying the properties of concrete, enhancing the ITZ, and reducing its carbon footprint. Six different concrete mixes with OSA doses between 10% and 30% and a constant BF dose of 8.0 kg per 1 m3 of concrete were prepared and tested. The ITZ was analysed with SEM images and verified through its mechanical properties. The results showed that the presence of OSA improved bonding and densified the microstructure of the paste, especially in the ITZ, resulting in a nearly constant flexural strength at up to a 20% replacement and only a 6.7% decrease in compressive strength while reducing the global warming potential by 19.24 kg CO2 equivalent in the mix with 10% OSA replacement. Higher replacement ratios had a negative impact on the mechanical properties, as the OSA had not reacted entirely and served partly as an inert filler.
